The present invention relates to a new and distinct cultivar of Begonia, of the family Begoniaceae, and given the cultivar name, ‘TNBEGTRS’. The new cultivar originated from a cross between a proprietary, unreleased unnamed, unpatented, rhizomatous Begonia seedling, as the seed parent, and an unnamed Begonia rex-cultorum seedling, as the pollen parent. This selection is uniquely characterized by:                1. rex type leaves with swirling leaf bases,        2. leaves show a subtle splatter pattern overall,        3. leaves colored celadon green on outer half of leaf and purple red in center half, and edged in purple red in the warm temperatures,        4. leaves colored rose red in center ⅔ and edges with a band of silver between in the colder temperatures,        5. a dense, bushy habit,        6. medium pink flowers in winter, and        7. excellent vigor.        
Compared to the seed parent, a proprietary, unreleased rhizomatous Begonia seedling, the new cultivar has a different leaf shape and has a strongly spiral sinus and displays a subtle spatter pattern rather than defined color zones.
Compared to the pollen parent, an unnamed Begonia rex-cultorum seedling, the new cultivar has a different leaf shape and displays a spattered color pattern rather than a solid red color.
Compared to sibling Begonia ‘St. Nick’, U.S. Plant Pat. No. 26,811, the new cultivar has a higher crown count, less leaf lobing, and leaf colored leaves colored celadon green on outer half of leaf and purple red in center half, and edged in purple red in the warm temperatures, leaves colored rose red in center ⅔ and edges with a band of silver between in the colder temperatures, rather than with a starry red center surrounded by emerald green with white polka dots.
The new variety has been reproduced only by asexual propagation (leaf cuttings and tissue culture). Each of the progeny exhibits identical characteristics to the original plant. Asexual propagation by micropropagation as done in Canby, Oreg., shows that the foregoing characteristics and distinctions come true to form and are established and transmitted through succeeding propagations. The present invention has not been evaluated under all possible environmental conditions. The phenotype may vary with variations in environment without a change in the genotype of the plant.